1. Field of the Invention
The present invention relates to a wave gear drive having a flexible external gear that can be made compact and small and also has a high rigidity.
2. Related Art Description
There has known a wave gear drive that has a flexible external gear. Typically, this flexible external gear comprises a cylindrical body, a circular diaphragm extending outward in a radial direction from one open end of the body, a circular boss formed integrally on a circumferential outer peripheral edge of the diaphragm, and external teeth formed on a circumferential outer surface of the other open end portion of the body.
The invention proposes a wave gear drive that can be made small and compact in structure, especially in length measured along an axial direction thereof. For example, such a wave gear drive is disclosed in Japanese Laid-Open No. Hei 8-312730 assigned to the same assignee of the present invention.